Dissertation (MA Linguistics)Tanzania is privileged with enormous linguistic diversity. It is estimated that there are more than 150 Ethnic Community languages in Tanzania, many fall under Bantu languages. Other groups are Nilotics, Cushites, Swahili, Khoisans, Arabs, Indians and others. Osogo (1979), the largest language group in terms of number is the Sukuma with over five million native speakers. Next to it is Nyamwezi, Ha, Chagga and Makonde to mention a few. Wanyaturu who speak Kinyaturu ranks number ten in respect to the number of native speakers. The theoretical framework used to guide this study was Batibo's (1992) marked bilingualism model. The research aimed at assessing the impact of Kiswahili on ECLs and Chahi dialect of Kinyaturu which was taken and studied as a case study. They are estimated today to have been about one million speakers of Kinyaturu. Their habitat is Singida region. The data of this study were collected through Questionnaires, Interview sessions and participant observation. The data collected were then analysed through the description and statistically presented. The area of the field was Ikungi District in Singida region. The data were mainly collected from Mang'onyi Ward. For the purpose of enriching the study, other areas where other dialects of Kinyaturu were visited which included Mtinko, Ilongero, Sepuka, Mungaa and Ihanja Wards in Singida and Ikungi districts. The major findings of the study reveal that there is a serious and great threat to Kinyaturu. The findings show that Kinyaturu though is spoken by a large community; it is faced with a serious threat from Kiswahili since most domains of language use are taken by Kiswahili leaving Kinyaturu with informal home domain only. It is very important for language stakeholders to take necessary measures of rescuing Kinyaturu from further loss. The research greatly challenges linguists, anthropologists, sociologists, government and the Tanzanians, in general, to wake up and stop this linguistic "Colonialism" in Tanzania and Africa in general. This has stirred the linguistics students' to conduct more researches on other languages and raise their voices to the policymakers with the aim that they will act accordingly to safeguard these heritage languages.